Abstract : A method is proposed for the determination of aluminum in zirconium and titanium powders. A sample is dissolved in a mixture of hydrofluoric, nitric, and sulfuric acids and the solution is evaporated to fumes of sulfuric acid. Water is added and an aliquot of the solution is pipetted into a plastic beaker containing hot sodium hydroxide solution. The solution is diluted to 200 ml of which 100 ml is filtered. The filtrate is neutralized to phenolphthalein with hydrochloric acid and the aluminum is determined spectrophotometrically by the use of aluminon. The following factors affecting the spectrophotometric determination of the aluminum were investigated: volume of solution during the color development, adjustment of acidity prior to addition of composite aluminon reagent, heating time in boiling water, amount of aluminum, wave length at which transmittance is measured, stability of the color, and interference of sodium sulfate, sodium chloride, zirconium, titanium, vanadium, chromium, and tin. (Author)